Underground mining system

ABSTRACT

Hydraulic underground mining system adapted to operate through a small diameter well bore and into a subterranean body and including a mining capsule carried on the lower end of an elongate support structure. The mining capsule includes a liquid jet nozzle at its upper end for forming a laterally directed jet stream to impact material in the ore body and to pulp the same into a slurry. An orifice having a grate for preventing entry of excessively large material is positioned below the jet so that freshly pulped slurry flows into the orifice, the latter being connected to an elongate positive displacement pump mounted below the orifice. Suitable hydraulic power means are provided for operating the pump and for progressively moving the jet stream .[. .]. .Iadd.through .Iaddend.at least a portion of an arc. Fixed liquid jets are also provided at the pump inlet for flushing and priming and to the lowermost portion of the capsule and to facilitate movement of the apparatus in the well bore.

BACKGROUND OF THE INVENTION

This invention relates to underground mining. More particularly thisinvention relates to a hydraulic underground mining system in whichmining at significant depths is accomplished by means such that ahydraulic mining fluid is introduced as a jet within a subterranean orebody to form a slurry in which form the ore is removed and brought tothe surface.

Subterranean mining of ore bodies by hydraulic mining through well boreshas been known, as for example, as set forth in the patent to Aston U.S.Pat. No. 2,518,591. Such mining takes place by slurrification ofmaterial in a subterranean mineral deposit and removal of the slurrifiedmaterial. In the past, jet pumps have been used to lift the slurry outof the mining area. However, the use of jet pumps limits the lift heightto .[.valves.]. .Iadd.values .Iaddend.which are inadequate for many orebodies. In addition, jet pumps tend to require large quantities ofmotive water which results in a very dilute slurry having too low asolids content. This results in consumption of excessive energy andwater.

Pressure lift systems have also been proposed, as for example, in theU.S. Pat. No. 3,439,953 to Pfefferle. In such systems, a well borecasing is sealed to the surrounding ground and sufficient pressure isthen applied in the subterranean deposit, i.e., internally of the orebody to expel slurrified contents through a conduit to the surface. Sucha pressure system is relatively expensive to operate due to weight andpower required to make up for seepage loss caused by the porosity of theregion surrounding the mined area and also due to the difficulty ofmaintaining a casing seal under pressures adequate to drive theslurrified material to the surface. Such systems are also subject tocasing failure or to failure of the seal. Where the casing or seal hasfailed, mining through that bore usually becomes impractical and if theoverburden subsides upon loss of pressure the entire rig may beunrecoverable. In addition, most prior art systems have required largewell bores, often in excess of 2 feet. The cost of drilling large wellbores is often too high to permit economic recovery of even shallow oredeposits. There is therefore, a need for a new and improved subterraneanmining method and apparatus.

SUMMARY OF THE INVENTION AND OBJECTS

In general, it is an object of the present invention to provide a newand improved hydraulic underground mining system which will overcome theabove limitations and disadvantages. It is a further general object ofthe invention to provide an underground mining system of the abovecharacter capable of efficient mining and removal of the mined materialas a high solids content slurry in which the water utilized in themining operation is also used as the suspending liquid for the slurry.

A further object of the invention is to provide an underground miningsystem of the above character capable of operation through a smalldiameter well bore at depths significantly greater than one hundredfeet.

A further object of the invention is to provide a hydraulic undergroundmining system of the above character in which there is no requirementfor a seal between the well bore casing and the lateral supportingearth.

A further object of the invention is to provide an underground miningsystem of the above character which eliminates the use of pressure forslurry removal and which has inherently high efficiency and economy ofoperation.

A further object of the invention is to provide a particularly novelunderground mining apparatus.

The foregoing objects are achieved by providing an underground miningsystem adapted to operate through a well bore drilled into asubterranean body to be mined. The well bore is small in diameter and isdrilled completely through the portion of the body to be mined and afurther substantial distance below it to provide for insertion of themining apparatus as will be described. The mining apparatus includes anelongate support structure having a diameter slightly smaller than thewell bore and including a mining capsule carried at its lower end. Theupper end is suspended in a suitable manner at the ground level as bybeing carried on a truck mounted drill rig or on a support flange. Themining capsule includes means at its upper end for hydraulically mininginto the ore body including jet means for developing a laterallydirected liquid jet stream to impact material in the body and pulp thesame into a slurry. Below the jet means a discharge sump is formedincluding a grate for preventing excessively large chunks of materialfrom entering the sump. Means is also provided for moving the jet backand forth through at least a partial arc so that the jet progressivelyimpinges upon material to pulp the same. The material thereafter flowsbackwardly toward the jet and into the discharge sump. An elongatepositive displacement pump is positioned in the sump and has an inletconnected thereto so that pulp slurry flows through the grate and intothe pump under gravity. Hydraulic power means drive the pump andsuitable piping is provided for supplying hydraulic motive power to apump motor and to the means for moving the jet nozzle. Additional pipingis provided for supplying liquid under high pressure to the jet nozzleand for serving as a slurry discharge line.

These and other objects and features of the invention will becomeapparent from the following description thereof when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 is a cross-sectional view partly broken away and partly inschematic form of an underground mining system constructed in accordancewith the present invention.

FIGS. 2A and 2B are isometric views of the mining capsule portion of themining system of FIG. 1.

FIGS. 3A, 3B, 3C and 3D are enlarged elevational views of the miningcapsule of FIGS. 2.

FIG. 4 is a cross-sectional view taken along lines 4--4 of FIG. 3B.

FIG. 5 is a cross-sectional view taken along lines 5--5 of FIG. 3B.

FIG. 6 is a cross-sectional view taken along lines 6--6 of FIG. 3C.

FIG. 7 is a cross-sectional view taken along lines 7--7 of FIG. 3D.

FIG. 8 is a cross-sectional view taken along lines 8--8 of FIG. 3D.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is adapted to be operated from a relativelyconventional drilling rig 10 having a suitable hoist 12. Such a rig istypically truck mounted and is adapted to move from place to place overa subterranean ore body. As shown, a well bore 14 is drilled through theore body 16 and down into the formations beneath the same to providespace for the mining apparatus 18 of the present invention. Afterdrilling, the well bore may be lined if desired down to the depth of theupper portion ore body. In many situations the sufficient lateralstability exists after drilling that lining of the hole will not benecessary, suitable capping being sufficient.

As shown in FIG. 1, the mining apparatus includes an upper portion 20serving as an elongate support structure which is made up of severalsections sufficient to obtain the desired depth so that the miningcapsule 22 carried on the lower end is positioned for operation into theore body.

Referring now particularly to FIGS. 2 through 8, the mining capsuleportion of the apparatus of the present invention will now be describedin detail after which the supporting connections of the upper portion ofthe structure together with the ground level associated facilities willbe described.

In general the mining capsule includes in its upper section a meansforming a liquid jet nozzle 30 immediately below which is mounted aslurry discharge opening 32 having a grate 34 thereover preventing theentry of excessively large particles. The opening communicatesinteriorly of the capsule with the inlet 36 of a slurry discharge pump38 constructed in elongate form and positioned below the jet and grateso that entering slurry flows into the pump under gravity.

The entire capsule is suitably supported in an elongate cylindricalsleeve 40 terminating in its upper end in a transverse flange 42. Thisflange positions several piping elements of the structure and is one ofseveral located throughout the length thereof for vertical support andpositioning purposes. A high pressure water or hydraulic inlet pipe 44is connected through a rotatable bearing assembly 46 to the input of aliquid jet nozzle 30. Immediately preceding the nozzle is a section 50of expanded pipe diameter containing a plurality of straightening vanes52 to assist in maintaining laminar flow of liquid or water through thepipe to the nozzle. The structure of the straightening vanes and nozzleas such are disclosed in co-pending application entitled Liquid JetNozzle, Ser. No. 213,363 filed Dec. 29, 1971, and assigned to the sameassignee as the present application. The bearing 46 may be of anysuitable type provided it is capable of withstanding internal liquidpressure. The rotatable portion of the bearing is integrally attached tothe upper or inlet end of the nozzle. The nozzle makes a turn through90° and terminates in a discharge orifice 54 which opens laterally tothereby direct a high velocity liquid jet stream into impact contactagainst the material in a portion 55 of the adjacent body to be mined.The lower end of the nozzle is provided with a turning lug 56 which isconnected through a drive shaft 58 to an oscillating motor locatedbeneath a seal flange 60 defining the upper end of a motor well 62 atthe lowermost end of the mining capsule. (See particularly FIG. 2B) Theshroud or casing is provided with an opening 64 therein (seeparticularly FIGS. 2A and 3B). The opening extending about an arc ofabout 270° to 320° in front of the nozzle orifice in this way, theliquid jet nozzle is rotated through a substantial arc from one side toanother in an oscillating pattern, thereby progressively moving theregion of impact of the liquid jet stream within the body from onelocation to another. As the material is pulped into slurry form, itflows backward toward the capsule where it is removed through opening32.

Means is provided for forming opening 30 immediately below the liquidjet nozzle. The opening is covered with grating 34 which preventsexcessively large chunks of material from entering, such chunks beingheld out and eventually reimpacted by the liquid jet stream and brokenup. The opening serves as the inlet to an elongate positive displacementpump 38, positioned below the orifice and connected thereto. The upperend of the pump terminates in a relatively large diameter slurrydischarge line 72 which extends upwardly to ground level and terminatesin an outlet over a discharge pond or vessel 74. Additional pumpingfacilities 76 may be incorporated in the line to provide boosterservice.

The pump is preferably of the elongate progressive cavity type commonlyknown as a Moyno (registered trademark) type, having a outer resilientshell or stator 78 with an inwardly facing helically formed surface.Within the outer shell is positioned a rotor member 80 having anoutwardly facing helically formed surface with one fewer turns than thestator 78. Such structures are known to be useful as pumps and aredisclosed by way of example in U.S. Pat. Nos. Re. 21,374 dated Feb. 27,1940 to R. Moineau and 2,505,136 dated Apr. 25, 1950 also to R. Moineau,and many others. The outer member is typically constructed of resilientmaterial which facilitates its use for handling any slurriable materialthat can be pushed through a pipe. Such pumps are of a positivedisplacement type because the rotor and the stator difference in turnsdefines a cavity which is progressively moved in one direction oranother as the rotor is rotated. Such pumps are commercially availablefrom the Moyno Pump Division of Robbins & Meyers, Inc., Springfield,Ohio. The pump is driven by hydraulic motor 81 mounted in the lowermostsection of the capsule in motor compartment 62.

The motor is connected through a universal drive coupling 82 to therotor 80 of the pump, the drive coupling arrangement being shownparticularly in FIGS. 3D and 6 through 8. As particularly indicated inFIG. 3C, the lower end of the rotor terminates in offset relationship tothe axis of the pump so that as the same is rotated the lower end iscaused to precess or wobble about the axis. The universal drive now tobe described accommodates the axial rotation of the drive motor to theprecessive movement of the pump rotor. The drive shaft terminates ateach end in a spherical, dental element drive, the detailed constructionof each of which is the same and is shown in FIG. 8. Thus, the drivingor driven shaft terminates in a two part housing bolted together andcontaining therein upper and lower thrust bearings 90, 92 havingradially facing inward thrust bearing surfaces 94, 96 lying in contactwith a ball 98 splined to the drive shaft 95. The upper and lowerbearings are disposed to bear above and below the ball surface so thataxial thrust load can be taken in either direction through the coupling.A suitable flexible seal 100 is retained in position between a retainingring 102 and lock collar 104 at the shaft end of the coupling device andterminates in a radially spaced position between the inner thrustbearing 90 and the cap 88a of the housing. Rotary motion is carriedthrough the coupling by means of a plurality of teeth 106 carried on theouter circumference of the ball, the teeth engaging between the teeth108 of a ring 110 carried in fixed position in the housing andsurrounding the ball.

FIGS. 6 and 7 show sectional views which locate the various componentsintermediate the motor well and the pump.

Suitable hydraulic piping and connections are provided and consist of apair of input lines 110, 112 and output lines 114, 116 to each of themotors.

In addition to the foregoing, a flushing nozzle jet 118 is connected tothe high pressure water source through suitable piping 120. This jet isclearly seen in FIG. 2B and is used to control the liquid content of theslurry pumped through the pump during operation so as to assure that itdoes not become an undue load on the pump. The jet is also useful forflooding the pump during start-up.

Preferably an additional high pressure water jet nozzle 122 ispositioned through the bottom flange 124 of the mining capsule housingand is directed downwardly to facilitate raising and lowering theassembly through the well bore. Suitable piping 126 connects nozzle 122to the high pressure water supply.

For the purpose of operating the several functions of the nozzles andmotors suitable valves 128 through 134 are incorporated in the variouslines. A pump 136 connecting the high pressure water lines to a waterreservoir 138. A separate pump 140 connects the hydraulic line tohydraulic reservoir 142. Valve 128 is arranged for reversible operationto provide for reverse the pump.

In operation, the apparatus of the present invention is lowered into thepredrilled well bore in stages a convenient length being about twentyfeet per stage. As each stage is lowered, it is held on to by suitablegripping means while the next stage is connected. Upon reaching thepredetermined depth for operation the entire unit is supported inposition by the drilling rig. If necessary, valve 134 and nozzle 122 maybe operated to flush material upwardly from the lower end of the wellbore and thereby facilitate movement of the assemblage downwardly. Afterproper positioning the valves 128 are open and hydraulic mining iscommenced. As the jet nozzle is oscillated, the jet stream cuts thematerial within the ore body and causes it to be pulped into a slurryand flow backward to the capsule where it drains into the opening 30 anddelivered through the elongate slurry pump and pumped to the surface. Byoperating through a limited arc less than a full circle sufficientmaterial remains in the vicinity of the well bore to prevent grosssubsidence at the surface. As the material is removed, the overburdenfrom within the cavity formed in the region of the removed materialusually collapses once the mining radius reaches a significant distance.As a practical matter, distances of up to seventy-five feet can be minedfrom a single well bore utilizing the apparatus of the presentinvention.

Using the present invention, many underground ore bodies can be minedeven though they exist at significant depths. The only requirements arethat the material to be mined be reasonably friable, unconstituted, andunconglomerated. Sands, gravel, phosphate ores, friable coals, anduranium ore are examples of materials which can be mined using thepresent invention.

To those skilled in the art to which this invention pertains, manymodifications and adaptations thereof will suggest themselves.Accordingly, it should be understood that the specific disclosures anddescriptions contained herein are to be taken in an illustrative senseand that the scope of the invention is not to be limited thereby exceptin accordance with the accompanying claims.

We claim:
 1. Hydraulic mining apparatus for operating through a wellbore drilled into a subterranean body to be mined, comprising anelongate support structure, means for suspending said support structurein said well bore, a mining capsule carried on the lower end of saidsupport structure, said mining capsule comprising means at its upper endfor hydraulically mining said ore body including jet means fordeveloping a laterally directed liquid jet stream to impact material insaid body and pulp the same into a slurry, means for moving said jetmeans back and forth through at least a partial arc, means forming adischarge orifice positioned below said jet and including grate meansfor preventing excessively large chunks of material from entering saidorifice, means forming an elongate positive displacement pump positionedbelow said orifice and connected thereto so that pulped slurry flowsthrough said grate and orifice and into pump under gravity, hydraulicpower means for driving said pump, piping means for connecting saidhydraulic power means to the ground level end of said apparatus, and aslurry discharge line connected to the outlet end of said pump, saiddischarge piping extending upwardly to the ground level end of saidapparatus and through said support structure.
 2. Hydraulic miningapparatus as in claim 1 in which said positive displacement pump is of alinear type including means for forming a succession of cavitieslinearly arranged and progressively moveable in either direction of saidpump whereby said pump may be reversed or operated in a positive senseto provide for flushing and start-up pumping.
 3. Apparatus as in claim 2further including a flushing jet connected to the inlet end of said pumpfor flooding the same during start-up and for controlling the liquidcontent of slurry during operation.
 4. Hydraulic mining apparatus as inclaim 1 further including a cylindrical shroud extending the length ofsaid apparatus and serving to stabilize the well bore in which saidapparatus is positioned.
 5. Hydraulic mining apparatus as in claim 1 inwhich said pump and the .[.motor.]. .Iadd.power .Iaddend.means foroperating said pump and for moving said jet means are located in thelowermost portion of said capsule and beneath said orifice.
 6. Hydraulicmining apparatus as in claim 1 including a flushing jet positioned atthe lowermost end of said apparatus and directed downwardly therefromfor facilitating movement of said apparatus in said well bore. .Iadd. 7.Mining apparatus for operating through a subterranean bore extendingfrom the exterior surface of the ground and into a subterranean body offriable material to be mined, comprising support means, a miningassembly carried by the support means within the bore and in the regionof the body, the mining assembly being a compact structural unitdimensioned with respect to the dimensions of the bore to enable thesame to be transported into the bore to a desired position within thebody, the assembly unit including jet means for discharging a liquid jetstream into the body to impact the material in the body and pulp thesame into a slurry, means for moving the jet means through at least apartial arc whereby a cavity is progressively formed in the body fromwhich the slurry flows toward the assembly unit, the assembly unithaving an opening located below the zone of operation of the jet meansand disposed to receive the slurry flow, a grate disposed in the openingfor preventing excessively large chunks of material from entering saidopening, an elongated mechanical pump forming a part of the assemblyunit and having an inlet at one end of the same and a discharge outletat the other end, the inlet being connected to receive slurry flowingthrough the opening and the grate, the pump being in general alignmentwith the bore, means for driving the pump, means including pipingconnected to the outlet of the pump and extending through the bore fromone end of the unit to the ground surface for the discharge of slurry,and means including piping extending through the bore from the groundsurface for delivering liquid under pressure to the jet means. .Iaddend..Iadd.
 8. Mining apparatus as in claim 7 in which the bore extendsdownwardly and the assembly is an elongated unit that includes the jetmeans, the grate, and the pump, and means for supplying driving power tothe pump from the surface of the well. .Iaddend. .Iadd.
 9. Miningapparatus for operating through a well bore extending down into asubterranean body of friable material to be mined, comprising a supportmeans, a mining assembly carried by said support means within the wellbore, the mining assembly being a compact structural unit dimensionedwith respect to the dimensions of the bore to enable the same to betransposed into the bore to a desired position within the body, saidmining assembly unit comprising means for hydraulically mining said orebody including jet means for developing a laterally directed liquid jetstream to impact material in said body and pulp the same into a slurry,means for moving said jet means through at least a partial arc whereby acavity is progressively formed in the body from which the slurry flowstoward the assembly unit, means forming a slurry receiving openingpositioned below the zone of operation of the jet means and includinggrate means for preventing excessivley large chunks of material fromentering said opening, an elongated mechanically driven pump forming apart of the assembly unit and having an inlet at one end of the same anda discharge outlet at the other end, the inlet being connected to theopening so that pumped slurry flows through said grate and opening andinto the intake at the lower end of said pump, the pump being in generalalignment with the bore, means for supplying driving power to the pumpfrom the upper ground surface, a slurry discharge line connected to theoutlet of the pump, said discharge line extending upwardly through thebore to the ground level, and means including piping extending throughthe bore from the ground surface for deliverying liquid under pressureto the jet means. .Iaddend. .Iadd.
 10. Mining apparatus as in claim 9 inwhich the assembly is in the form of an elongated unit which includesthe jet means, the slurry receiving opening and grate means, and thepump, all disposed along the length of the unit. .Iaddend.